This research will test models concerning the impact of specified parenting behaviors in combination with severe symptoms of parental anxiety, environmental risk and protective factors, in a high-risk sample of children of parents with panic disorder (PD), in order to examine child fear arousal across the first two years of life. Four-month infants from two parental diagnostic groups will be studied in order to increment the likelihood of risk: eighty infants with PD mothers and eighty infants of mothers without psychopathology. Infant fearful behaviors in response to novel stimuli and neurobiological indicators of arousal (baseline and potentiated startle, salivary cortisol and sleep disturbances), along with parental anxiety symptoms, specified parenting behaviors, and environmental risk and protective factors, will be assessed at four, fourteen and twenty-four months of age. Caregiver-infant interactions are expected to play an important role in contributing to increasing infant fear-arousal for constitutionally vulnerable infants during this period. This research will provide information concerning which particular factors might contribute to increasing child fear-arousal across the first 2 years of life.